1. Field of the Invention
The present invention relates to a capsule-type medical device that is inserted to a living body to perform image pickup, etc.
2. Description of the Related Art
Endoscopes, which enable diagnostic examinations, or treatments as necessary, of a body cavity by inserting an insertion portion to the body cavity have come into wide use in the medical and other fields.
Also, recently, a capsule-type medical device including a capsule-type in-vivo device having the shape of a capsule (abbreviated to “capsule”), which is swallowed from the mouth to pick up images in the body cavity, thereby enabling an endoscopic examination, has been put into practical use.
When a capsule is inserted into a body cavity, it ordinarily moves in the body cavity by means of peristaltic movement or the like, and accordingly, it is sometimes desirable to know information obtained by the capsule corresponds to which site in the body.
Therefore, as a first related art example, for example, Japanese Patent Application Laid-Open Publication No. 2003-524448 discloses the art in which a signal sent wirelessly from a capsule in a body cavity via an antenna is received by a plurality of antennae arranged outside the body to calculate the position of the capsule from, e.g., the intensity of the received signal.
Also, as a second related art example, Japanese Patent Application Laid-Open Publication No. 2005-198789 discloses the art in which a signal sent wirelessly via an antenna of a capsule in a body cavity is received by a plurality of antennae arranged outside the body to calculate the position and direction of the capsule from, e.g., the intensity of the received signal.
Meanwhile, when the position of a capsule is estimated, multiple positions may be estimated because of noise, etc.
Where multiple positions have been estimated as mentioned above, it is difficult to determine the track of the movement of the capsule unless the positions of the antenna in the capsule at respective times are determined, lowering the utility value of information on the inside of the body, etc., obtained by the capsule.